Tells the delegate that all the video rendered by the Google Mobile Ads SDK has stopped playing
sound. Your app can now resume any music playback or produce any kind of sound. Note that this
message doesn’t mean that all the video has stopped playing, just audio, so you shouldn’t
deactivate AVAudioSession’s instance. Doing so can lead to unexpected video playback behavior.
You may deactivate AVAudioSession only when all rendered video ads are paused or have finished
playing, and ‘audioVideoDidPauseAllVideo:’ is called.